1. Field of the Invention
This invention relates to a semiconductor device which is capable of wireless communication.
2. Description of the Related Art
In recent years, an individual identification technology using wireless communication through an electromagnetic field, a radio wave, or the like has attracted attention. Specifically, as a semiconductor device which performs data communication through wireless communication, an individual identification technology which employs RFID (radio frequency identification) tags (e.g., non-contact IC (integrated circuit) tags, RF tags, wireless tags, electronic tags, transponders, or data carriers) has attracted attention. Individual identification technology which employs RFID tags (hereinafter referred to as RFID) is beginning to be made use of in production, management, and the like of individual objects, and it is expected that this technology will also be applied to personal authentication.
In order to obtain higher resistance to external force or the like and also flexibility, the above-described semiconductor device such as RFID has a structure in which a functional circuit body is sealed with a sealant such as resin. The thickness of the resin needs to be thin in order to make a semiconductor device flexible; however, resistance to external force cannot be adequately enhanced if the resin is thin, whereby the possibility of breaking is increased.
As an example of a measure against breaking due to external force, a structure in which a plurality of circuits having the same function is provided to increase redundancy (e.g., Patent Document 1: Japanese Published Patent Application No. 2002-083277). By providing the plurality of circuits having the same function (hereinafter those circuits are referred to as redundant circuits), when a defect due to breaking by external force or the like is detected in one of the plurality of circuits having the same function, another one of the plurality of circuits can be operated instead of the one judged as defective.